XmlNotepad 2006 and XmlCsvReader
Two new findings...
XmlNotepad 2006 is a free Xml Editor that I've just got a hold of and it looks very handy. It's not quite overkill which I feel XmlSpy is. Nice and simple, with validation, xslt transformations, and so on. Have a look if you haven't already...
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnxmlnet/html/xmlnotepad.asp
The other, which you'll want in your toolset, is XmlCsvReader by Chris Lovett. This is a reader that parses CSV files and lets you access them as XML. Now that is really handy.... convert all those legacy files, just like that!! Bravo Chris!! It comes with source code so is an ideal reference for creating your own legacy file to xml reader.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnxmlnet/html/xmlcsvreader.asp